Microbial sedimentary imprint on the deep Dead Sea sediment

Abstract

A study of an International Continental Drilling Program core recovered from the middle of the modern Dead Sea has identified microbial traces within this subsurface hypersaline environment. A comparison with an active microbial mat exhibiting similar evaporative processes characterized iron-sulphur mineralization and exopolymeric substances resulting from microbial activity. Exopolymeric substances were identified in the drilled sediment but unlike other hypersaline environments, it appears that they have a limited effect on the precipitation of calcium carbonate in the sedimentary column. Sulphate reduction, however, plays a role in all types of evaporative facies, leading to the formation of diagenetic iron sulphides in glacial and interglacial intervals. Their synthesis seems to occur under progressive sulphidation that generally stops at greigite because of incomplete sulphate reduction. The latter may be caused by a lack of suitable organic matter in this hypersaline, hence energy-demanding, environment. Pyrite may be found in periods of high lake productivity, when more labile organic matter is available. The carbon and sulphur cycles are thus influenced by microbial activity in the Dead Sea environment and this influence results in diagenetic transformations in the deep sediment.

Magnetic Properties of Late Holocene Dead Sea Sediments as a Monitor of Regional Hydroclimate

“…These minerals form as products of two reactants that form during early diagenetic anoxic microbial processes: (1) reactive iron (Fe 2+ )-which is a product of microbial iron (Fe 3+ ) reduction and (2) sulfide (S 2− )-which is a product of MSR. Bishop et al (2013) and Thomas et al (2016) suggested that the transformation from monosulfide to pyrite in Dead Sea sediments requires addition of S°. For microbial iron and sulfate reduction to occur, an adequate supply of labile organic matter, iron (Fe 3+ ), and sulfate are required.…”

The First Catalog of Archaeomagnetic Directions From Israel With 4,000 Years of Geomagnetic Secular Variations

“…This could be a result of inclination shallowing, post depositional magnetization, and smoothing of the sedimentary data. As the Holocene Dead Sea sediments are dominated by authigenic greigite (Ron et al, 2006;Frank et al, 2007b;Thomas et al, 2016;Ebert et al, 2018) a complicated magnetic acquisition mechanism is expected. Thus, differences between the archaeomagnetic and the sedimentary data are likely.…”

Fluid inclusions from the deep Dead Sea sediment provide new insights on Holocene extreme microbial life

“…Torfstein et al, 2005). It is also the case for magnetic minerals such as greigite or titanomagnetite (Ebert et al, 2018;Thomas et al, 2016). The microorganisms responsible for this sulfate reduction however remain unknown.…”